drive: Discard stream reader canceller as soon as the required data is obtained.

chrome/browser/chromeos/drive/drive_file_stream_reader.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_FILE_STREAM_READER_H_
 #define CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_FILE_STREAM_READER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 70 matching lines @@
   // invalidate its weak pointers before other members are destroyed.
   base::WeakPtrFactory<LocalReaderProxy> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(LocalReaderProxy);
 };
 
 // The read operation implementation for the file which is being downloaded.
 class NetworkReaderProxy : public ReaderProxy {
  public:
   // If the instance is deleted during the download process, it is necessary
   // to cancel the job. |job_canceller| should be the callback to run the
-  // cancelling.
+  // cancelling. |full_content_length| is necessary for determining whether the
+  // deletion is done in the middle of download process.
   NetworkReaderProxy(
-      int64 offset, int64 content_length, const base::Closure& job_canceller);
+      int64 offset, int64 content_length, int64 full_content_length,
+      const base::Closure& job_canceller);
   virtual ~NetworkReaderProxy();
 
   // ReaderProxy overrides.
   virtual int Read(net::IOBuffer* buffer, int buffer_length,
                    const net::CompletionCallback& callback) OVERRIDE;
   virtual void OnGetContent(scoped_ptr<std::string> data) OVERRIDE;
   virtual void OnCompleted(FileError error) OVERRIDE;
 
  private:
   // The data received from the server, but not yet read.
   ScopedVector<std::string> pending_data_;
 
   // The number of bytes to be skipped.
   int64 remaining_offset_;
 
   // The number of bytes of remaining data (including the data not yet
   // received from the server).
   int64 remaining_content_length_;
 
+  // Flag to remember whether this read request is for reading till the end of
+  // the file.
+  const bool is_full_download_;
+
   int error_code_;
 
   // To support pending Read(), it is necessary to keep its arguments.
   scoped_refptr<net::IOBuffer> buffer_;
   int buffer_length_;
   net::CompletionCallback callback_;
 
   // Keeps the closure to cancel downloading job if necessary.
   // Will be reset when the job is completed (regardless whether the job is
   // successfully done or not).
@@ skipping 85 matching lines @@
 
   // This should remain the last member so it'll be destroyed first and
   // invalidate its weak pointers before other members are destroyed.
   base::WeakPtrFactory<DriveFileStreamReader> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(DriveFileStreamReader);
 };
 
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_FILE_STREAM_READER_H_